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9 Appendix - Technical Terms
DivX
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DivX is the name of a revolutionary new video codec which is based on the new MPEG-4 compression
standard for video. When you install a video codec on your system it basically works as an add-on to your
system with instructions on how to compress/decompress video in that video format. Once you've installed
the DivX codec on your system you will be able to play DivX movies using Windows Media Player or any
other DivX-enabled player.
Despite the fact that DivX movies offer better compression and higher quality video than regular MPEG
movies it takes more time to encode due to the incredible compression technology. The DivX codec makes it
possible to compress/encode a full-length movie at near DVD-quality, which is small enough to fit on a single
CD (700MB). The DivX video is usually combined with MP3 audio to produce both high quality video and
audio.
XviD
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XviD is the name of a new open-source video codec, which like the DivX is based on the new MPEG-4
compression standard for video. It's currently being developed by people from all over the world. When you
install a video codec on your system, it basically works as an ‘add-on’ to your system with instructions on
how to compress/decompress video in that video format. Once you've installed the XviD codec on your
system you will be able to play XviD movies using Windows Media Player or any other XviD-enabled player.
MPEG
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MPEG stands for Motion Picture Experts Group. This is the same group that made the MPEG-1 (used in
VideoCDs), MPEG-2 (used in DVD and SuperVCDs and other high bandwidth systems) and MPEG-4 (ASF,
DivX, WMV, low-mid bandwidth systems) standards. They are also responsible for MP3 (MPEG Audio Layer
3) and AAC audio compression standards.
VOB
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VOB stands for Video Objects. DVD movies are stored in VOB files. Each VOB file has a number of
video/audio/subpicture streams.
SUBPICTURE
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A subpicture stream found in VOB files normally refers to the subtitles. Subtitles on DVDs are not stored as
"text," but rather as a video stream. A subpicture stream is one that overlays on top of the main picture
stream (ie. the movie), and on a DVD the subpicture stream can be turned on and off.
AVI
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AVI stands for Audio Video Interleave. AVI is a file format, like MP3 or JPG. But unlike these formats, AVI is a
container format, meaning it can contain video/audio compressed files using many different combinations of
codecs. Therefore, while MP3 and JPG can only contain a certain kind of compression (MPEG Audio Layer 3
and JPEG), AVI can contain many different kinds of compression (eg. DivX video + WMA audio or Indeo
video + PCM audio) as long as a codec is available for encoding/decoding. All AVI files look the same on the
"outside", but on the "inside", they may be completely different. Almost all tools on this site are not just DivX
tools, but also AVI tools, so will work with many other codecs.
AC3
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Initially known as Audio Coding 3, AC3 is a synonym for Dolby Digital these days. Dolby Digital is an
advanced audio compression technology allowing to encode up to 6 separate channels at bit-rates up to
448kbit/s. For more information please check out the Dolby website.
DTS
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By supplying film studios with outstanding techniques for delivering soundtracks to an attentive audience,
DTS digital sound is now featured on virtually 100% of major Hollywood releases. Although the technology
